सभी प्राणियों की मूल संरचनात्मक एवं कार्यात्मक इकाई जिससे प्राणियों का निर्माण हुआ है।

(biology) the basic structural and functional unit of all organisms. They may exist as independent units of life (as in monads) or may form colonies or tissues as in higher plants and animals.